Then I typed again sudo apt-get dselect-upgrade -y. This is the error:

Reading package lists... Done
Building dependency tree
Reading state information... Done
You might want to run 'apt-get -f install' to correct these.
The following packages have unmet dependencies:
libxslt1-dev:i386 : Depends: libxml2-dev:i386 (>= 2.6.26) but it is not installed
E: Unmet dependencies. Try using -f.

And trying to sudo apt-get -f install:

Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following extra packages will be installed:
libxml2-dev:i386
The following NEW packages will be installed:
libxml2-dev:i386
0 upgraded, 1 newly installed, 0 to remove and 6 not upgraded.
5 not fully installed or removed.
Need to get 0 B/761 kB of archives.
After this operation, 2,206 kB of additional disk space will be used.
Do you want to continue [Y/n]?
(Reading database ... 372874 files and directories currently installed.)
Unpacking libxml2-dev:i386 (from .../libxml2-dev_2.7.8.dfsg-5.1ubuntu4.3_i386.deb) ...
dpkg: error processing /var/cache/apt/archives/libxml2-dev_2.7.8.dfsg-5.1ubuntu4.3_i386.deb (--unpack):
'./usr/bin/xml2-config' is different from the same file on the system
Processing triggers for man-db ...
Errors were encountered while processing:
/var/cache/apt/archives/libxml2-dev_2.7.8.dfsg-5.1ubuntu4.3_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

Other people had similar problem and I tried to follow this answer, but without being able to solve. Can you help me?